What can we learn from the relative performance of the front-running Audis and
Toyotas as the stage is set for the 90th anniversary 24 Hours race?

Le Mans 2013 starts at 15.00 (local) time on Saturday. What should have been six hours of qualifying for grid positions was bowdlerised by early stoppages, and ended at midnight with a nagging feeling that some people weren't revealing as much as they might. Much like the test day, the weather was a) bad and b) unpredictable; but even between downpours, accidents and resultant red flags, it was difficult to believe much of the evidence.

In a nutshell, we are either looking at one of Le Mans' simpler walkovers, or someone has been pulling the wool over our eyes, for now. In which, latter, case we may still be in for a race to do the 90th anniversary justice, and that's what most observers are predicting.

The fight for pole position was the start of the battle for outright victory, which will come from an LMP1 prototype, and more precisely from the hybrid division of the LMP1 ranks, which now dominates as surely as diesel-power did from 2006 to 2011. There's a difference, though. Audi started the diesel era with a debut win for the R10 TDI, Peugeot joined in, kept the Germans honest for five years, and beat them once (in 2009). But while the Audi and Peugeot diesels were different enough to be interesting (the Audis were mostly open cars, for example, where the Peugeots were always coupés), a diesel was still essentially a diesel, German or French.

With the advent of hybrid technology last year, and the re-appearance of Toyota (with the TS030 to challenge Audi's equally new R18 e-tron quattro), technical diversity returned – which is something the Le Mans rule-makers always try to encourage.

So now we have a turbocharged-diesel Audi with flywheel/electric hybrid system and part-time "quattro" drive via electric motors to the front wheels; and facing it, a non-turbo petrol-engined Toyota with super-capacitor hybrid system and rear-drive only. Very different.

Having bestowed freedom of choice, the rule-makers strive valiantly to achieve balance of performance. So your petrol engine (with or without hybrid adjunct) can be up to 3.4 litres without or 2.0 litres with turbocharging. And your diesel can be 3.7 litres, and will be turbocharged because without it, relatively speaking, it wouldn't have the power to get out of its own way. The blanket LMP1 weight limit is 900kg, but 'manufacturer' cars (for which read hybrids) suffer another 15kg, not to penalise them but to help the privateers, of which there are three this year – two Rebellion Lola coupés and an open Strakka HPD. Both are petrol, the Rebellions powered by Toyota, the Strakka HPD by Honda. And they get a bit more help with a smaller intake air restrictor, plus a slower refuelling flow for the hybrids – intended to make a hybrid (ie manufacturer) pit-stop eight to 10 seconds longer than last year.

All of which is why a headline time in P1 qualifying, however spectacular, is a great deal less than half the story, and why we may sound sceptical of what we've seen so far.

To whit, three Audis topping the sheets (more or less through every session and every type of weather), two Toyotas, then the "petrol class". The fastest, number 2 Audi (in spite of theoretically performance-reducing supplementary regulations for this year) has gone faster than last year's pole position, faster than its test day best, and the thick end of four-and-a-half seconds faster than the fastest Toyota. Which nobody understands, as the much-changed 2013 Toyota has been impressive at Silverstone and Spa, but has struggled here to beat last year's times. Always assuming it has tried to, of course, and there's the nub.

Also in the interests of balance, the petrol cars have a fuel capacity advantage over the less thirsty diesels – 73 litres versus 58 litres. But the petrol-hybrid Toyota has been given another 3 litres of its own, which the smart money says lets it go a lap further between stops. Not that three litres will get you around a lap; it won't, not by a very long way. But if 73 litres would get you around eleven-and-seven-eighths and 76 will get you around 12, you've gained a whole lap – because seven-eighths of a lap is no use to man nor beast.

The best guess is that the Audis will do 10 laps between fuel stops, the Toyotas 12. Over, say, 385 laps, Toyota could be six or seven stops to the good. That's a lot of time, enough to keep them far closer to the faster Audis over 24 hours. But it doesn't nullify the apparent deficit of 4.3 seconds on the grid for faster Toyota to pole-sitting Audi, much less the 8.5 seconds of the slower one, which was actually behind Rebellion's fastest non-hybrid.

Yet there were relaxed smiles in the Toyota garages, and no conspicuous outbreaks of head-scratching or navel-gazing, so who knows what they know that we don't?

If (and it's still if) Toyota hasn't revealed its true potential, it has sacrificed only the transitory glory of pole position to keep a massive card up its sleeve. At 10 laps, as the Audis peel into the pits for the first time, the Toyotas run on for two laps more, and can reveal themselves to be as fast as they need to be. Or not, but that will be the dénoument.

Meanwhile, the pure petrol P1s will be going a bit further yet, putting on miles again while the hybrids are taking their refuelling medicine. Not that they're going to win, but it does provide another twist. If the Toyotas aren't sandbagging after all, it might ultimately be the faster Rebellion chasing the tail-gunner Audi, not Toyota. That would make a good race, too, and by Saturday supper-time we might finally know the truth.